1. Field of the Invention
The present invention relates to an electronic apparatus, such as a single chip microcomputer, which is suitable for use with electronic equipment to be controlled thereby.
2. Description of the Related Art
With electronic equipment such as commercial video cam-corder and miniaturized video decks, single chip microcomputers mounted within the main body of the electronic equipment have conventionally been used to provide control of all or part of this kind of electronic equipment.
This kind of single chip microcomputer usually has a structure consisting of commonly known items such as a central processing apparatus (CPU) for carrying out processes such as control of accesses to the storage means and arithmetic processes, storage apparatus such as a read only memory (ROM) for permanently storing information, and a random access memory (RAM) capable of reading and writing and peripheral circuits such as input/output ports. All of these structures are generally integrated onto a single chip.
Electronic apparatus having this kind of single chip integration has an advantage in that large scale cost reduction can be realized due to mass production. In addition to this, due to the fact that the size of program to be stored in a ROM has drastically increased as semiconductor integrating technology has advanced it has also become possible to control versatile and complicated items in accordance with the programs stored in the ROM.
Thus, it has become possible to control versatile and complicated items using a large amount of programs stored in the ROM. However, enlarging the size of the program stored in the ROM has resulted in the problem of generating bugs in the program.
Particularly, in the case where a bug is discovered after mass production, a production re-run is perform to produce bug-corrected microcomputers to replace those mounted in the electronic equipment, or alternatively, the electronic equipment is attached with a bug-correcting external part. Either of these alternatives have, however, been excessively expensive. In addition, as electronic equipment such as video cam-corders has a very high packing density, the attachment of external parts has virtually been impossible to carry out. The present invention has been made to solve these problems.